There is a vast difference between those because price and nutritional value are objective measures. One Piece doesn't cost less or have different "ingredients" so that comparison doesn't fit.
There
are objective measures in story telling. Consistency of plot, character consistency, quality of character development, lore consistency, quality of world building, quality of fight choreography etc. etc.
Sales success is because of popularity. A popular but objectively bad product will make more money than an unpopular but objectively good product.
One Piece is art. You can love Beethoven and hate Prince or vice versa, but that in no way would imply a value difference between them, they're both highly valued within their realms and successful in general.
People can love an objectively poorly written story or hate an objectively well written one. Their love or hate of it is irrelevant in regards to the quality of the product though.
Besides, if there is no objective metric to story telling then there are no good story tellers, only successful ones.
Is that what you are arguing?